feat: integrate IGV reports links into HTML and XLSX outputs

[berntpopp]

Currently, IGV reports are generated separately and linked via JSON map. Integrate these links directly into the HTML and XLSX outputs to allow quick and easy navigation from variants table to the IGV visualization.
Proposed Changes:

• Update HTML template to include clickable links or icons in each variant row linking to the IGV report.
• If XLSX is generated, add a column linking to IGV reports (as URLs or notes).
  Benefits:
• Enhances interactivity and usability of the final reports.
• Streamlines the variant review process by providing one-click access to IGV views.
  Acceptance Criteria:
• IGV links appear in the HTML report and are clickable.
• XLSX includes IGV links if generated.
• Documentation updated with instructions on how to use the integrated links.